You’ve probably seen it on your anesthesia form, called “Physical Status”. It’s the classification system used to assess the health of patients prior to anesthesia. Studies show that the score you assign to your patient can be an important predictor of the outcome of a procedure. It’s simple: patients with a higher score have a higher risk of anesthetic complications.

The American Society of Anesthesiologists (ASA) adopted a physical status scoring system that’s a subjective assessment of overall health based on five classes.

Patient is a completely healthy fit patient (ex: young patient for elective surgery)

Patient has severe systemic disease that is not incapacitating (ex: compensated renal failure)

Patient has incapacitating disease that is a constant threat to life (ex: congestive heart failure)

A moribund patient not expected to live 24 hour with or without surgery (ex: acute anaphylactic shock)

“E” is placed after the number when the procedure is an emergency. An emergency is when a delay in treatment would significantly increase the threat to the patient’s life or body part.

Being simple and widely understood, the value of the ASA score has been frequently validated in clinical research studies. In one study of 3,438 elective total hip and total knee arthroplasty patients (human), the ASA score correlated significantly to the incidence of postoperative death. The study showed that class III patients had a higher risk of postoperative death than patients with lower ASA scores.

ASA scores also correlate well with operating time, hospital stay, infection rate, and overall morbidity and mortality. The strength of this association has been well documented and can be considered a predictor of postoperative outcome. So, picking a number between 1 and 5, and assigning your patient its ASA physical status score, is a great way to prepare yourself to protect the life of your patient.

Ken Crump (kencrump.com) is a writer and animal anesthetist and writes Making Anesthesia Easier for Advanced Anesthesia Specialists. He makes dozens of Continuing Education presentations on veterinary oncology and anesthesia across the United States and in Canada. Ken retired from Colorado State University in 2008.